In the Darkness
by IceGirl2772
Summary: They brought her into their world, now she's bringing them into hers. What could possibly go wrong? It's self-explanatory, isn't it? Leo/OC T to be safe (but mainly because I'm paranoid)


**Hey! This is my first time writing in this archive. I can't promise I'll be good, but I can promise to do my best.**

 **I own nothing except my OC. I'm also posting this on archiveofourown and I'll try to update them both at the same time, but I hold no promises because, you know, life gets in the way.**

 **I own nothing except my OC. If I did...honestly, I don't know what I would do differently.**

 **ENJOY!**

 **...or not...**

* * *

" _COME BACK HERE!"_

 _That was something she would not do._

 _The five-year-old girl ran as fast as her tiny legs could carry her. Pushing her way through the busy streets and past the hoard of people walking on its footpaths. The people she was pushing past were so self-obsessed and narrowly focused on their own goals, they didn't even think twice about the little girl. Instead, some would verbally abuse her._

 _But she did not care. She had to get away from him._

 _She turned into an alleyway, only to find herself facing a dead end._

 _She could hear him come closer, his yells as he calls her many things, him telling her to stay still and she wouldn't get it as bad._

 _Yeah._ _ **As bad**_ _._

 _She knew she could potentially make things worse for herself, but she had to hide._

 _She saw a manhole cover. And usually, when there's a manhole cover, there's a way into the sewers._

 _He would never follow her down there._

 _On average, manhole covers weighed around fifty kilograms, so it was an amazing feat for her to be able to move it enough for her to climb into the sewers._

 _She did not have time to stop to reposition the manhole cover. He was stronger and faster than her. Any delay could have her in his grasp once again._

 _So she just climbed down the ladder and began running._

 _She could not tell you how long she was running – or how far she had come – when she finally came to a stop._

 _Her lungs burned. Her side ached. Her leg throbbed from when she fell down. Everything she had not noticed before suddenly hit her full force, and she was left unable to move._

" _WHERE ARE YOU, YOU WORTHLESS BRAT?!"_

Oh no. Her plan didn't work. He did decide to follow her down after all.

" _Pssst…"_

 _What was that?_

" _Over here!"_

 _Should she be following that strange voice. Even if it did sound like it was around her age, she didn't know if she should trust it._

 _Then she heard_ _ **him**_ _again and decided that she didn't have anything to lose._

 _She went to the entrance of the tunnel where she heard the voice, only to feel something grab her hand and pull her deeper into the tunnel._

 _She had to bite her lip hard to keep herself from crying out due to the pain her side and leg were causing her._

 _Eventually, they stopped running. She could no longer hear the voice of the man, but she couldn't take the chance of exposing herself just yet._

" _You'll be safe here," the voice reassured her._

" _Who are you?" she asked, speaking for the first time since the whole incident started._

" _I'm…," the voice then hesitated._

 _Why was he so afraid to tell her his name?_

" _It might be best if I show you," he finally decided, "But you have to promise not to scream. Or run. Or tell anyone you saw me down here."_

" _Why are you…?" she trailed off._

" _Just promise me!" the voice pleaded._

 _"OK, OK! I promise!" she sighed in frustration._

 _Slowly, he let go of her hand – and she just realized it was different to others – and began approaching the pool of light a grate above them was providing. She could hear the water sloshing under his feet as he walked into it to get to the grate._

 _What she saw surprised her._

 _A_ _ **turtle**_ _._

* * *

A lot can change in ten years.

The girl from the sewers can vouch for that as she climbed down that ladder – the one she had climbed down many times before – with a backpack on her back. When she hit the bottom, she checked that her 'accessories' were still on her.

A throwing axe and a tanto. Check.

She then decided to do one final check of her backpack, figuring that if she had forgotten something, now would be the optimum time to go back to retrieve it.

Well, as optimum as it could be.

Satisfied, she continued on her journey, blowing away a strand of brown hair that did not want to stay in its place and silently thankful that she always wore her hair in a braid.

She could hear voices as she got closer to her destination.

"There's a little more algae and worms left if anybody wants it. Anybody? Anybody…?"

That made her cringe. Algae and worms did not sound nice individually, but the thought of having them **together**?

Might as well hand her a bucket at the thought of it.

The three others agreed with the first voice.

"No thanks."

"I'm good."

"All yours."

"Well, I guess no one left room… for cake!"

As she walked through the living area and towards the kitchen, she could see the 'cake' the first voice – belonging to an orange-masked turtle – mentioned. A middle-aged rat just sat there contently as his students gawked at the cake.

The other three Turtles voiced her thoughts for her.

"WHOA!"

"IT IS A CAKE!" the purple-masked Turtle gasped excitedly.

"Made with…," the red-masked Turtle trailed off as he saw the worms crawling around while tasting a bit, "Algae. And worms."

"What's the frosting made out of?" the blue-masked Turtle asked nervously.

"You don't wanna know," the orange-masked Turtle cringed.

"Well, with Mikey in the kitchen, it could really be anything, couldn't it?" the girl remarked, making herself known to the group as she walked in.

" _ **ALINA!**_ "

Before she knew it, she was almost tackled to the ground by Mikey, who hugged her happily.

"I missed you too, Mikey," Alina chuckled.

"Took you long enough to get here," the red-masked Turtle drawled as he pulled Mikey off of her.

"Yeah, Raph. There's this place I have to attend called school," Alina deadpanned as she placed her backpack in the corner, deciding to give them their presents later.

"Be nice, Raph! She may withhold our presents!" Mikey warned him.

"Well, only from some of you," Alina mused, looking at Raph pointedly.

Raph waved her off, "Happy you came, Als."

"You missed training this morning," the purple-masked Turtle pointed out, "Raph beat me with my staff."

"Didn't drop the staff?" Alina guessed.

"Didn't drop the staff," the purple-masked Turtle sighed.

"Donnie, just grab his sais and beat him up with them," Alina suggested.

"Like that'll ever happen!" Raph scoffed.

"Hey! What about me?!" the blue-masked Turtle joked.

"Sorry, Leo," Alina giggled slightly as she walked into his waiting arms.

Leo smiled as he softly kissed her on the cheek. It happened by accident one day after training and the next thing they knew, it became _their_ thing.

"Oooh… Leo and Alina sitting in a tree! K-I-S-S-I-N-OOOF!"

"Michelangelo, I do not approve of those childish games. Especially when they keep making it clear they are not…dating," the rat, known as Master Splinter, trailed off, struggling to remember the right word.

Things have changed considerably since he was their age.

"Thank you," Leo and Alina sighed in relief.

"Happy Mutation Day, boys!" Alina cheered.

"HAPPY MUTATION DAY!" the boys yelled just as enthusiastically.

"Ah yes. 15 years ago today, our lives changed forever and we became the unlikeliest of families," Master Splinter mused.

"Tell us the story, Master Splinter!" Mikey pleaded.

"Michelangelo, I have already told it many times," Master Splinter replied.

That didn't stop Mikey from begging. Only Raph placing a firm hand over his mouth did that.

"Please. It's the only way to shut Mikey up," Raph pointed out.

"Very well," Master Splinter sighed, "Only if our guest does not object."

"Hey. It's their birthday," Alina shrugged.

Nodding, Master Splinter began his tale, "Many years ago, when I was still human, I was leaving the pet store with four baby pet turtles."

"THAT WAS US!" Mikey cut in.

"Yes. Don't interrupt," Master Splinter scolded before resuming his story,

"I passed a strange man on the street. Something felt off about him. I decided to follow. 'Go no further. This place is a place where you are not allowed to be in this place. We have been seen in this place by you, so this is a place that will not be left by you.'"

Alina remembered the story vividly, having heard it many times herself. Master Splinter, then known as Hamato Yoshi, was leaving the pet store with the Turtles when he bumped into a strange man on the street. He followed the man and saw him exchanging a canister filled with a strange ooze with another man, but gave his position away by stepping on a brown rat's tail. He fought the man and his companion valiantly. However, during the fight, the canister broke and doused Yoshi and the Turtles with the strange ooze. The five of them mutated into the last things they came into contact with. Having come into contact with the rat, Hamato Yoshi mutated into a humanoid brown rat. Having come into contact with their new owner, the Turtles became humanoid Turtles.

Holding the broken canister, Master Splinter finished his tale, "That was the beginning of our life together. It was the mysterious substance in this canister that, in a way, gave birth to us all."

Alina couldn't help but look at Mikey weirdly as he held the canister tightly and called it his mother.

"Then five years later," Master Splinter continued as he turned to face Alina, "We gained a new member of our family when Leonardo found Alina in the sewers."

Oh yeah. Alina remembered that day well.

* * *

" _You're a turtle!" Alina gasped in surprise._

 _She did keep her word. She didn't run or scream at the sight of the humanoid Turtle before her._

" _There's a reason why I'm down here," Leo stated, "I'm Leo, by the way."_

" _Alina," Alina introduced herself._

" _So you're not scared?" Leo asked timidly._

" _You saved me. Why would I be scared of you?" Alina remarked before asking just as timidly, "But how did you get this way?"_

" _That's a story for my Sensei to tell. You should come meet him and my brothers," Leo suggested excitedly, "And you can hide from the bad man with us."_

 _Alina wasn't sure what happened next. All she knew was she was being led to the lair…_

 _And his sensei wasn't happy._

" _Leonardo," Master Splinter scolded, "What did I tell you about bringing strangers to the lair?!"_

" _But she's hurt, Sensei!" Leo began objecting, "I couldn't leave her there."_

" _Oooh… Lame-o-nardo broke the rules," Raph drawled as he, Donnie and Mikey walked in._

 _"She's pretty," Mikey drooled._

" _She's also scared," Donnie stated._

 _Eyes softening at the sight of her, Master Splinter knelt before her and reassured her, "Do not worry, my child. I promise that as long as you are with me and my sons, you will always be safe."_

 _Master Splinter then offered his hand to her. At first, she shied away, almost hiding behind Leo. Tentatively, she stepped forward and reached out her hand. Trusting people did not come easy to her. After hesitating once more, she finally placed her hand in his._

 _And a friendship began._

* * *

When Master Splinter returned to his meal, Alina took the opportunity to whisper to Leo,

"Have you asked him yet?"

Unfortunately, Alina wasn't that quiet. Well, she was, but Master Splinter's acute hearing picked up her question.

"Asked me what?" Master Splinter wanted to know.

Hesitantly, Leo began broaching the topic, "So, Sensei, now that we're 15, I think we're finally ready to go up to the surface with Allie, don't you?"

"Yes," Master Splinter nodded, causing the Turtles to cheer excitedly, "And no."

The happiness the Turtles initially had quickly disappeared and they began voicing their objections.

"I hate it when he does that!" Raph moaned.

"You have grown powerful, but you are still young. You lack the maturity to use your skills wisely," Master Splinter said as he got up to walk away.

"So, Sensei, is that just no?" Donnie asked.

"Yes… and no," Master Splinter responded, "Wisdom comes from experience, and experience comes from making mistakes."

"Ah-ha!" Donnie cried, "So in order for us to gain the wisdom, we have to make the mistakes. So we can go!"

"No," Master Splinter shook his head.

"And yes?" Donnie asked hopefully.

"No!" Master Splinter said firmly, causing Donnie to moan in disappointment and frustration.

Alina decided to take over, "Master Splinter, I know you're trying to protect them. But they have been waiting for the chance to go up for as long as I've known them. I promise that I will never leave their side on the surface."

"We can't spend our whole lives hiding down here," Leo decided to chime in.

Master Splinter turned away, stroking his beard while reflecting on what two of his students and surrogate children had said.

When he turned back, he saw four Turtles on their knees giving him what Alina referred to as the 'puppy-dog eyes'.

That broke his resolve.

"You may go. Tonight," Master Splinter relented.

He heard cheers, ranging from the traditional 'Yes!' to Mikey's catchphrase, 'Booyakasha!'

"HIGH THREE!" Mikey cheered.

Four Turtle hands and one human hand clapped together in celebration.

They still had a bit to go before nightfall, where the Turtles could wonder freely. Everyone did something to kill the time.

Leo and Alina decided to watch a cult classic TV show called _Space Heroes_.

"Mr. Crankshaw, status report!"

"Status? I'll give you the status! We're gonna blow up in two seconds! (slap) Thank you, Captain."

Leo recited the next line along with the ship's captain,

"Gentlemen, I have a bold and daring plan. There's no time for hesitation. My orders must be carried out without question."

"You know this show is stupid, right?" Raph said from his position on the couch, without looking up from his comic book.

" _Space Heroes_ is a great show and Captain Ryan is a great hero!" Leo objected, "And someday, I am gonna be just like him!"

"Well, you do like to hear yourself talk, so you're on your way," Raph shrugged.

"As much as I like Captain Ryan, there's better things to aspire to," Alina pointed out.

"Like what?" Leo scoffed.

"You for one thing," Alina retorted.

Before they could say anything else, Mikey and Donnie ran into the living room.

"It's go time!" Mikey cheered.

Hurriedly, the five of them suited up, grabbing their weapons, which they had stored in the dojo. Donnie was quick to grab his bo-staff, while Raph grabbed his two sais (which Alina made the mistake of referring to as 'salad tongs' once), Leo grabbed his twin katana and stored them in their sheaths, Mikey grabbed his twin nunchucks and Alina grabbed her axe and tanto, sliding them into their respective compartments on the belt of her jumpsuit.

Once they had their weapons, they stood before Master Splinter in a line as he spoke to them before their trip,

"You are going up to a strange and hostile world. You must maintain awareness at all times. You must also listen to Alina. She knows more about the surface than you do. Just as she will watch over you, you also must watch over her."

"Hai, sensei," the five teenagers chorused before turning to leave.

"Stay in the shadows!" Master Splinter instructed.

"Hai, sensei," the five teenagers nodded.

"Don't talk to strangers!" Master Splinter warned them, earning a less-than-enthusiastic 'Hai, sensei' from his students, "Everyone is a stranger!"

"Hai, sensei," the five teenagers sighed before attempting to leave.

"Make sure you go before you leave! The restrooms up there are filthy!" Master Splinter ordered.

Alina had to agree with Master Splinter, but she was also annoyed.

"SENSEI!" the five teenagers cried impatiently.

"Good luck, my sons," Master Splinter finally sighed.

Happily, the four Turtles and Alina jumped over the turnstiles and began running towards the sewers.

They could hear Master Splinter shout his final warning,

"Look both ways before crossing the street!"

Alina decided she was going to take them to the manhole she always used to get to them. Leo went up first, pushing the manhole cover off slightly so he could see if the coast was clear. Satisfied, he pushed it off all the way and jumped out. Grabbing Alina's hand, he helped pull her out while Donnie, Raph and Mikey climbed out behind them.

Alina watched as the four brothers took in their first sights of New York – from the graffiti on the walls, the dumpster on one side, to the homeless man sleeping on a dodgy mattress using a well-used newspaper as a flimsy blanket.

The sights did nothing for Alina. Having been in New York for the last ten years, she was used to it.

But her friends weren't, and they eagerly drank in what was around them.

"It's so beautiful!" Mikey gasped.

Ten years ago, the Turtles have welcomed Alina into their world, filled with ninjitsu, sewers, and algae and worms. Finally, Alina could welcome the Turtles into her world.

What could possibly go wrong?

* * *

 **Meh. You guys know the drill. I'll try to be quick.**

 **By the way, I don't intend to rewrite EVERY episode with her in it. I'll reference them, maybe include a scene or two, but I'll only do the ones I feel will contribute to the story. I'm just gonna do _Rise of the Turtles_ to get that backbone for the story.**

 **BUH-BYE!**


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